Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606	$ 67,269	$ 35,832	$ 236,759	$ 149,602
Noninterest income	118,810	94,258	388,827	307,480
Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606	35	(214)	310	(192)
Noninterest income	25,470	34,384	82,899	88,504
Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606	5,172	3,194	15,017	3,194
Noninterest income	6,506	4,241	18,863	4,241
Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606	1,684	1,834	6,597	1,883
Noninterest income	23,383	23,315	65,704	62,470
Other noninterest income
Disaggregation of Revenue [Line Items]
Revenue out of scope of ASC 606	60,378	31,018	214,835	144,717
Noninterest income	63,451	32,318	221,361	152,265
Consumer Banking
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	47,440	54,623	139,310	146,479
Consumer Banking | Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	23,010	32,552	75,130	84,453
Consumer Banking | Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	1,334	1,047	3,846	1,047
Consumer Banking | Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	21,635	21,479	59,041	60,584
Consumer Banking | Other noninterest income
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	1,461	(455)	1,293	395
Commercial Banking
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	3,902	3,640	11,991	11,154
Commercial Banking | Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	2,425	2,046	7,459	4,243
Commercial Banking | Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	0	0	0	0
Commercial Banking | Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	64	2	66	3
Commercial Banking | Other noninterest income
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	1,413	1,592	4,466	6,908
Enterprise Services
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	199	163	767	245
Enterprise Services | Fees and service charges on deposit accounts
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	0	0	0	0
Enterprise Services | Wealth management revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	0	0	0	0
Enterprise Services | Card and ATM revenue
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	0	0	0	0
Enterprise Services | Other noninterest income
Disaggregation of Revenue [Line Items]
Revenues within the scope of 606	$ 199	$ 163	$ 767	$ 245